Just my own here but I gotta disagree. I watched my dad die a pretty quick death, long term diabetes complications. I cared for him while my mom had to be at work. He wanted to die at home. I have seen sepsis up close and personal, and until you've changed those dressings and dealt with septic wounds, you just cannot imagine how quickly that infection moves, even with proper treatment. I can only imagine how quickly it would move if untreated.
I am not discounting your theories as I find them equally valid and possible. I just have to say, based on my own life experience and having seen it myself, the sepsis thing, really could shut down major organs within days.
Therefore, I can't dismiss that theory any more than I can dismiss yours at this point.
ETA Sepsis would not, however, explain to me why LE took that drywall from Z's room, unless part of the coverup began there. If that drywall shows evidence of bodily fluids such as blood, etc. Then I may be more willing to discount the septic theory.